1. Field of the Invention
The present invention relates to display devices for a vehicle. More specifically, the present invention relates to a display device for a vehicle which is capable of displaying a three dimensional (stereoscopic) image using a real image and a virtual image.
2. Description of Related Art
Japanese Unexamined Patent Application, First Publication No. Sho 64-52533 discloses a double reflection type virtual image display for vehicles which displays a three dimensional image using real images and virtual images. The display includes a first display, a half mirror, a reflection plate, and a second display. The first display is disposed so as to face the driver and displays a real image to the driver. The half mirror is provided with the first display which is disposed so as to be inclined towards the driver. The reflection plate is disposed at an upper position so as to oppose the half mirror and so as not to block the driver""s view. The second display displays a virtual image on the half mirror by projecting an image onto the reflection plate. In the above display for vehicles, virtual images are displayed at interior positions as compared with the positions of real images in the depth direction by increasing the distance between the half mirror, the reflection plate, and the second display, which is used for displaying virtual images, as compared with the distance between the half mirror and the first display. As a result, three dimensional images can be displayed by combining the real images with the virtual images.
However, in the above-mentioned publication, it is not explicitly disclosed what kind of information is displayed in what way. Accordingly, there is a danger that information necessary for a driver to read may not be clearly displayed for the driver if the selection of information data, which are displayed by using real images or virtual images, is incorrectly made. If the information necessary for the driver to read is not clearly displayed on the display, the driver has to spend unnecessary labor for monitoring or reading the displayed information, and the driver""s fatigue due to driving the vehicle may be increased by these actions. Accordingly, the manner in which the display content of real images and virtual images are selected and displayed is quite important.
The present invention takes into consideration the above-mentioned circumstances, and has an object to provide a display device for vehicles which is capable of reducing fatigue of a driver due to driving the vehicle. Other objects and features of the invention will be understood from the following description with reference to the accompanying drawings.
In order to achieve the above objects, the present invention provides a display device for a vehicle which includes a display unit (for instance, display units 12 and 54 explained in embodiments described below) which is capable of displaying a three dimensional image by shifting a position of a real image and a position of a virtual image in a front and back direction; and a total control unit (for instance, a CPU 13 explained in the embodiments described below) which controls a display content of the display unit. The total control unit includes a vehicle condition determination unit (for instance, a vehicle condition determination unit 30 explained in the embodiments described below) which determines the condition of the vehicle based on internal information data including at least vehicle speed information and external information data including at least information on another vehicle running in front of the vehicle; an information selection unit (for instance, an information selection unit 31 explained in the embodiments described below) which selects information data to be displayed on the display unit from the internal information data and the external information data based on the condition of the vehicle determined by the vehicle condition determination unit; and a display control unit (for instance, a display control unit 32 explained in the embodiments described below) which displays internal information data selected by the information selection unit on the display unit using real images, and external information data selected by the information selection unit on the display unit using virtual images.
According to the display device for a vehicle described above, when the vehicle condition determination unit determines the condition of the vehicle based on the internal information data including at least vehicle speed information and the external information data including at least information on another vehicle running in front of the vehicle, the information selection unit selects information data to be displayed on the display unit from the internal information data and the external information data based on the condition of the vehicle determined by the vehicle condition determination unit. Then, the display control unit displays internal information data selected by the information selection unit on the display unit using real images, and external information data selected by the information selection unit on the display unit using virtual images. By displaying the internal information data containing at least the vehicle speed information, i.e., information data particularly required to be read or understood by the driver, using real images in this manner, and the external information data including at least the information on a car in front, i.e., the information which may be better to be sensuously understood by the driver, using virtual images, it becomes possible to display the internal information more clearly.
In another aspect of the present invention, the display unit displays the real images in front of the virtual images.
According to the display device for a vehicle described above, since the display unit displays the real images in front and the virtual images at the back of the real images, it becomes possible to display the internal information more clearly by displaying the internal information data containing at least the vehicle speed information, i.e., the information data particularly required to be read or understood by the driver, in front using real images, and the external information data including at least the information on a car in front, i.e., the information which may be better sensuously understood by the driver, at the back using virtual images.
In yet another aspect of the present invention, the display unit (for instance, the display unit 12 explained in the embodiments described below) includes: a first display (for instance, a first display 17 explained in the embodiments described below) which displays a real image; a half mirror (for instance, a half mirror 18 explained in the embodiments described below) which is disposed at a driver side with respect to the first display; a total reflection mirror (for instance, a total reflection mirror 19 explained in the embodiments described below) which is disposed below and in the vicinity of the half mirror; and a second display (for instance, a second display 20 explained in the embodiments described below) which is disposed at the driver side with respect to the total reflection mirror and displays virtual images on the half mirror by projecting images onto the total reflection mirror.
According to the display device for a vehicle described above, since the half mirror is disposed at the driver side of the first display, and the total reflection mirror and the second display are disposed substantially below the half mirror and the first display, the display unit does not protrude towards the front glass side. Hence, it becomes possible to prevent the display unit from interfering with the driver""s view.
In yet another aspect of the present invention, the display unit (for instance, the display unit 54 explained in the embodiments described below) includes: a display (for instance, a display 55 explained in the embodiments described below) which includes a display area for displaying real images (for instance, a display area 56 for displaying real images explained in the embodiments described below) and a display area for displaying virtual images (for instance, a display area 57 for displaying virtual images explained in the embodiments described below), the display area for displaying virtual images being disposed at a driver side with respect to the display area for displaying real images; a total reflection mirror (for instance, a total reflection mirror 60 explained in the embodiments described below) which reflects a display content of the display area for displaying real images; and a half mirror (for instance, a half mirror 61 explained in the embodiments described below) which reflects a display content of the display area for displaying virtual images.
According to the display device for a vehicle described above, since real images and virtual images are displayed by using a display having a display area for displaying real images and a display area for displaying virtual images, which is disposed at the driver side with respect to the display area for displaying real images, only one display is necessary for displaying images.
In yet another aspect of the present invention, the display device for a vehicle further includes: a second display area for displaying virtual images (for instance, a display area 58 for displaying virtual images explained in the embodiments described below) which is disposed in the vicinity of a corner of the display area for displaying real images; and a second half mirror (for instance, a half mirror 62 explained in the embodiments described below) which reflects a display content of the second display area for displaying virtual images.
According to the display device for a vehicle described above, since the second display area for displaying virtual images is disposed in the vicinity of a corner of the display area for displaying real images and the second half mirror reflects a display content of the second display area for displaying virtual images, it becomes possible to increase the variation of displaying virtual images.
In yet another aspect of the present invention, the display control unit controls, when only internal information data selected by the information selection unit is displayed on the display unit by the display control unit using real images and this display state is changed to contain external information data in addition to the internal information data, so that a display position of the internal information data is shifted with respect to a display position of the external information data.
According to the display device for a vehicle described above, since the display control unit controls, when only internal information data selected by the information selection unit is displayed on the display unit by the display control unit using real images and this display state is changed to contain external information data in addition to the internal information data, so that a display position of the internal information data is shifted with respect to a display position of the external information data, it becomes possible to display both the internal information data and the external information data without being interfered with each other, and both the internal information data and the external information data can be clearly displayed in an excellent manner.